小分子有机酸对纳米铁稳定砷的影响

发布时间：2018-05-20 22:37

  本文选题：砷 + 纳米零价铁　； 参考：《环境工程学报》2017年05期

【摘要】：金矿开采后的尾矿中含有大量的砷,纳米零价铁可以有效稳定尾矿中的砷,但是在尾矿的后期复垦过程中,表层植被分泌的小分子有机酸,会使土壤中稳定的砷重新释放,造成二次污染。以植物根系分泌的常见小分子有机酸中的乙酸作为研究对象,在纳米零价铁(NZVI)去除砷的动力学基础上,利用批实验方法研究乙酸对稳定砷的影响过程。结果表明,纳米铁可以在几分钟内去除尾矿浸出液中的砷,反应符合准二级动力学模型,铁砷质量比约500∶1时,砷去除率可以达到94%以上。NZVI快速去除As(Ⅴ)主要是在NZVI表面的氧化铁上发生吸附、共沉淀作用。有氧条件下的NZVI对As(Ⅴ)去除效果优于无氧条件下的效果,长期有氧腐蚀NZVI对浮选尾矿和生物氧化尾矿的砷去除率比未腐蚀的分别增加了18.03%和15.21%。乙酸盐对长期有氧腐蚀NZVI稳定的浮选尾矿和生物氧化尾矿砷的解吸率比未腐蚀的分别减少了7.56%和20.01%。当乙酸(以三水合乙酸钠计)与纳米铁的质量比达到2.72∶1时,由于乙酸的羧基与砷酸根有相似的电荷类型,可以与砷竞争吸附铁氧化物表面的吸附位点,又可以与三价铁离子形成稳定的配合物,会使稳定的砷重新释放。但当铁砷质量比逐渐增大(大于5 000∶1),较多的吸附位点会有效抑制乙酸盐对砷的释放。
[Abstract]:There is a large amount of arsenic in the tailings after gold mining, and nanocrystalline zero-valent iron can effectively stabilize the arsenic in the tailings, but during the late reclamation of the tailings, the small molecular organic acids secreted by the surface vegetation will release the stable arsenic from the soil. Cause secondary pollution. Acetic acid in common small organic acids exudated by plant roots was used as the research object. Based on the kinetics of removing arsenic from NZVI, the effects of acetic acid on arsenic stabilization were studied by batch experiment. The results show that nanocrystalline iron can remove arsenic from the tailings leachate in a few minutes. The reaction accords with the quasi-second-order kinetic model, and the mass ratio of iron to arsenic is about 500: 1. The removal rate of arsenic can reach more than 94%. NZVI can remove as (鈪，

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